A variety of designs have been commercialized or proposed for instruments incorporating a pair of cooperating jaws (i.e., a jaw assembly) in which one or both jaws pivot or otherwise move between open and closed positions. Examples of such instruments include tissue graspers, tissue clamps, needle graspers, tissue cutters, linear staplers, ligating clip appliers, and the like.
In some surgical applications, it is necessary or advantageous to apply relatively high squeezing forces. Thus, it would be desirable to provide an improved actuation system with an amplification capability for increasing the jaw closure force compared to the operator input force. It would also be beneficial if the system could accommodate designs wherein the closure force can be varied during the closure stroke.
For example, when an open ligating clip is squeezed closed about tissue by means of jaws on a ligating clip applier, the initially open legs of the clip at first offer little resistance to the closing force. Only a relatively low compression force need be initially applied to each leg of the clip to pivot or deform the legs through a major portion of the leg travel. However, as the ligating clip legs compress the tissue and approach the fully closed configuration, the magnitude of the force required to continue moving the clip legs together can increase substantially. Accordingly, it would be desirable to provide a ligating clip jaw closure actuation system which could accommodate the increasing closure force that occurs with increasing jaw travel.
It would also be beneficial to provide an improved actuation system which could be substantially automatically responsive to an increased load and provide an increased actuator force in response.
In various surgical procedures, it is sometimes desirable to insure that a surgical instrument, once it has begun operation (e.g., closing a clip about tissue), continue that operation to completion rather than interrupt and prematurely terminate the operation. To this end, it would be advantageous if an improved actuation system could be provided with an anti-backup design. However, in some situations it may nevertheless desirable to knowingly terminate the instrument operation prior to completion of the instrument cycle. Thus, it would be beneficial to provide an improved actuation system that could accommodate the release or avoidance of the anti-backup feature.
It would further be desirable to provide an improved actuation system having a reduced number of components, such as mechanical linkages, rachet mechanisms, and the like, so as to reduce the number of components and so as to minimize friction losses.
Finally, it would also be beneficial if such an improved system could be provided with sufficient capacity and strength to accommodate relatively high loads during operation of the instrument.
The present invention provides an improved actuation system which can be used to operate a surgical instrument and which can accommodate designs having the above-discussed benefits and features.